EP1635621A2 - Rare gas fluorescent lamp lighting apparatus - Google Patents

Rare gas fluorescent lamp lighting apparatus Download PDF

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Publication number
EP1635621A2
EP1635621A2 EP05017710A EP05017710A EP1635621A2 EP 1635621 A2 EP1635621 A2 EP 1635621A2 EP 05017710 A EP05017710 A EP 05017710A EP 05017710 A EP05017710 A EP 05017710A EP 1635621 A2 EP1635621 A2 EP 1635621A2
Authority
EP
European Patent Office
Prior art keywords
voltage
circuit
rare gas
fluorescent lamp
power source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05017710A
Other languages
German (de)
English (en)
French (fr)
Inventor
Shinichi c/o Minebea Co. Ltd. Suzuki
Ryu c/o Minebea Co. Ltd. Terada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Minebea Co Ltd
Original Assignee
Minebea Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Minebea Co Ltd filed Critical Minebea Co Ltd
Publication of EP1635621A2 publication Critical patent/EP1635621A2/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/2806—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
    • H05B41/2813—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

  • the present invention relates to a rare gas fluorescent lamp lighting apparatus, and more particularly to a rare gas fluorescent lighting apparatus to light a rare gas fluorescent lamp as a light source in a document reading device, such as a facsimile machine, an image scanner, and a copying machine.
  • a document reading device such as a facsimile machine, an image scanner, and a copying machine.
  • a rare gas fluorescent lamp which emits light through rare gas discharging, is increasingly used as a light source for illumination in a document reading device, such as a copying machine, and an image scanner. It is well known that a rare gas fluorescent lamp is lighted with a high-intensity luminance when a high-frequency pulse voltage is applied, and a lighting apparatus with an inverter circuit to generate such a high-frequency pulse voltage is preferably employed for lighting a rare gas fluorescent lamp.
  • a rare gas fluorescent lamp lighting apparatus in which a DC-DC converter is put at the input side of the circuit to generate a high-frequency voltage thereby stabilizing electric power at the input side so that the light mount of a rare gas fluorescent lamp is stabilized without suffering the influence of the fluctuation of the input voltage (refer to, for example, Japanese Patent Application Laid-Open No. 2001-15284).
  • Fig. 18 is a block diagram of such a rare gas fluorescent lamp lighting apparatus as disclosed in the aforementioned Japanese Patent Application Laid-Open No. 2001-15284, in which a step-up DC-DC converter CV is provided at the input side of a high-frequency voltage generating circuit HC.
  • a second driving circuit CT in the DC-DC converter CV is adapted to feed a PWM modulated driving signal to a second switching element S2 based on a signal fed back from a current detecting circuit R so that a current detected at the current detecting circuit R has a constant peak value, whereby the output is controlled at a constant electric power without receiving the influence of voltage fluctuation of a DC power supply E1 thus stabilizing the light amount of a rare gas fluorescent lamp DL.
  • the second driving circuit CT is usually constituted as an IC, and therefore the entire cost is pushed up.
  • the present invention has been made in light of the above problems and therefore has as an object to provide a rare gas fluorescent lamp lighting apparatus, in which the amount of light is stabilized without suffering the influence of the voltage fluctuation of the input power supply and without deterioration of efficiency, and which is inexpensively fabricated with a smaller dimension.
  • a rare gas fluorescent lamp lighting apparatus which includes: an input power source; a transformer having a rare gas fluorescent lamp connected to a secondary side thereof; a switching element connected in series to a primary side of the transformer; and a drive block to drive the switching element.
  • the drive block includes: a triangular waveform oscillation circuit to increase and decrease oscillation frequency according respectively to an increase and a decrease in a voltage of the input power source; and a comparison circuit to transform a triangular waveform outputted from the triangular waveform oscillation circuit into a rectangular waveform with a predetermined duty ratio.
  • the drive block which drives the switching element connected to the primary side of the transformer, includes the oscillation circuit adapted to vary the frequency according to the variation of the input voltage, the voltage inputted to the primary side of the transformer can be maintained substantially constant, whereby the light amount of the rare gas fluorescent lamp is stabilized.
  • the drive block may further include: a constant voltage circuit to convert the voltage of the input power source into a constant voltage as an output; and a constant current circuit to output a charging current according to the voltage of the input power source
  • the triangular waveform oscillation circuit may include: an oscillator capacitor to be charged by the charging current of the constant current circuit and to be discharged at a predetermined time constant; and a comparator which switches between a charging mode and a discharging mode for the oscillator capacitor, and to which a threshold voltage resulting from division of the constant voltage from the constant voltage circuit, and a terminal-based voltage across both terminals of the oscillator capacitor are inputted, whereby the terminal-based voltage is outputted as a triangular waveform voltage.
  • the oscillation circuit is simply structured with the comparator and the capacitor as main components without employing circuit components for electric power control to stabilize the voltage of the input power source, the light amount of the rare gas fluorescent lamp can be stabilized without deterioration in efficiency, thus enabling downsizing and cost reduction.
  • Fig. 1 is a block diagram of a rare gas fluorescent lamp lighting apparatus according to an embodiment of the present invention
  • a rare gas fluorescent lamp lighting apparatus 50 generally includes an inverter circuit 6 connected to an input power source Vin, a drive block 10 to drive the inverter circuit 6, and a protection circuit 7 provided between the inverter circuit 6 and the drive block 10.
  • a rare gas fluorescent lamp DL containing a rare gas consisting mainly of, for example, xenon (Xe) is connected to the output side of the inverter circuit 6.
  • the inverter circuit 6 includes a transformer TR and a switching element Q1 connected in series to the primary side TRp of the transformer TR, and the switching element Q1 is constituted by, for example, an n-channel MOSFET.
  • the drive block 10 includes a constant voltage circuit 1 and a constant current circuit 2, which are connected to the input power source Vin, and further includes a triangular waveform oscillation circuit 3, a comparison circuit 4, and a drive circuit 5, which receive a voltage from the constant voltage circuit 1, and the output of the constant current circuit 2 is connected to the triangular waveform oscillation circuit 3.
  • the output of the drive circuit 5 is connected to the switching element Q1.
  • the constant voltage circuit 1 includes resistors R1 and R2, a zener diode ZD, and a transistor Tr1.
  • the connection portion of the resistor R1 and the zener diode ZD is connected to the base terminal of the transistor Tr1, and a constant voltage V set by a zener voltage of the zener diode ZD is supplied to the triangular waveform oscillation circuit 3, the comparison circuit 4, and the drive circuit 5.
  • the constant current circuit 2 includes variable resistors R3, R4, R5, R6 and R7, a diode D1, and a transistor Tr2.
  • the connection portion of the resistor R6 and the diode D1 is connected to the base terminal of the transistor Tr2, and a charging current Ic set by a voltage of the input power source Vin and resistance values of the variable resistors R3, R4, R5, R6 and R7 is supplied to the triangular waveform oscillation circuit 3.
  • variable resistors R3, R4, R5, R6 and R7 are set at respective predetermined values thereby supplying a constant current independent of a variation of a load connected to the collector terminal of the transistor Tr2, but when the voltage of the input power source Vin undergoes a variation, a voltage applied across both terminals of a series circuit consisting of the resistor R5 and the diode D1 is caused to vary, specifically increase and decrease according respectively to the increase and decrease of the voltage of the input power source Vin, which causes a current value set by the voltage and the resistor R7 to increase and decrease.
  • the constant current circuit 2 in the present embodiment is adapted to supply to the triangular waveform oscillation circuit 3 the charging current Ic which varies according to the variation of the voltage of the input power source Vin.
  • the constant current 2 may alternatively be constituted by a well known current mirror circuit.
  • the triangular waveform oscillation circuit 3 includes a comparator COMP1 and an oscillator capacitor C1 as main components.
  • a non-inverting input terminal COMP(+) of the comparator COMP1 is connected to the connection portion of resistors R8 and R9 which constitute a series circuit between an output voltage line 11 of the constant voltage circuit 1 and the ground and is connected also to an output terminal COMP1o of the comparator COMP1 via a feedback resistor R11.
  • the oscillator capacitor C1 has its one terminal connected to the inverting input terminal COMP(-) of the comparator COMP1 and has the other terminal grounded.
  • the one terminal of the oscillator capacitor C1 is also connected to the constant current circuit 2 via a diode 2 and to the output terminal COMP1o of comparator COMP1 via a diode D3 and a resistor R12.
  • the triangular waveform oscillation circuit 3 in the present embodiment is adapted to output to the comparison circuit 4 a triangular waveform voltage generated across both terminals of the oscillator capacitor C1, and the operation of the triangular waveform oscillation circuit 3 will be detailed later.
  • the comparison circuit 4 includes a comparator COMP2 and resistors R13 and 14.
  • the inverting input terminal of the comparator COMP2 is connected to the connection portion of the resistors R13 and R14 which constitute a series circuit between the output voltage line 11 of the constant voltage circuit 1 and the ground, and the aforementioned triangular waveform voltage as the output from the triangular waveform oscillation circuit 3 is inputted to the non-inverting terminal of the comparator COMP2.
  • the comparison circuit 4 in the present embodiment is adapted to compare the triangular waveform voltage with a threshold voltage resulting from the constant voltage V divided by the resistors R13 and R14, whereby a rectangular waveform voltage having a prescribed duty ratio is generated at an output terminal COMP2o of the comparator COMP2 and outputted to the drive circuit 5.
  • the drive circuit 5 is a push-pull current amplification circuit including transistors Tr3 and Tr4.
  • the drive circuit 5 is driven by the rectangular waveform voltage from the comparison circuit 4 so as to rapidly charge and discharge a capacitance between the gate and source of the switching element Q1 of the inverter circuit 6, thereby supplying a driving signal Vgs having a high-frequency rectangular waveform to the gate terminal of the switching element Q1.
  • the inverter circuit 6 includes, as described above, the transformer TR and the switching element Q1 connected in series to the primary side TRp of the transformer TR.
  • the switching element Q1 receives the high-frequency driving signal Vgs supplied from the drive circuit 5 and is thereby turned on and off.
  • a current Id which increases linearly, is caused to flow at the primary side TRp of the transformer TR, and energy is stored at the transformer TR.
  • the switching element Q1 is turned off, the current Id is cut off, and the energy stored is discharged to the secondary side TRs of the transformer TR, whereby an output voltage is induced at the secondary side TRs of the transformer TR and applied to the rage gas fluorescent lamp DL, and the rare gas fluorescent lamp DL is lighted.
  • a pulse voltage Vds according to the energy stored in the transformer TR is generated across the drain and source of the switching element Q1.
  • the protection circuit 7 is adapted to protect circuit elements against stresses generated during no-load discharge at the secondary side TRs of the transformer TR.
  • the protection circuit 7 detects a current flowing at the secondary side TRs of the transformer TR, whereby the drive circuit 5 is deactivated, for example, when the rare gas fluorescent lamp DL is not connected.
  • the operation of the protection circuit 7 will be briefly explained.
  • the current flowing at the secondary side TRs of the transformer TR is rectified by a diode D4 so as to charge a capacitor C4 thereby turning on a transistor Tr6, which causes electric charge stored at a capacitor C5 to be discharged, consequently turning off a transistor Tr5.
  • the aforementioned rectangular wave voltage is generated at the output terminal COMP2o of the comparator COMP2 of the comparison circuit 4 connected to the collector terminal of the transistor Tr5, and the drive circuit 5 is duly activated.
  • the capacitor C4 is discharged thereby turning off the transistor Tr6, which causes the capacitor C5 to be charged, consequently turning on the transistor Tr5. Accordingly, the output of the comparator COMP2 of the comparison circuit 4 is fixedly maintained substantially at the ground potential, and the drive circuit 5 is deactivated.
  • the oscillator capacitor C1 is charged by the charging current Ic supplied from the constant current circuit 2, and the voltage across both terminals of the oscillator capacitor C1 increases almost linearly during time period Tc as shown in Fig. 3C.
  • This voltage is inputted to the inverting input terminal COMP(-) of the comparator COMP1, and when the input voltage at the inverting terminal COMP(-) increases and reaches the threshold voltage V TH at time point t1, the output voltage at the output terminal COMP1o of the comparator COMP1 is switched to the low level as shown in Fig. 3A.
  • V TL (R/2) / (R + R/2) V ⁇ 0.33 V ⁇ V TH ) is inputted to the non-inverting input terminal COMP(+) of the comparator COMP1 during time period T D as shown in Fig. 3B.
  • the oscillator capacitor C1 is discharged via the diode D3 and the resistor R12, and consequently the voltage across both terminals of the oscillator capacitor C1 decreases by a time constant determined by the oscillator capacitor C1 and the resistor R12 (the time constant in the present embodiment is adjusted so that the voltage decreases almost linearly as shown in Fig. 3C).
  • This voltage is inputted to the inverting input terminal COMP(-) of the comparator COMP1, and when the input voltage at the inverting input terminal COMP(-) decreases and reaches the threshold voltage V TL at time point t2, the output voltage at the output terminal COMP1o of the comparator COMP1 is switched back to the high level.
  • the above-described operations during time periods T C and T D are repeated, and the triangular waveform voltage shown in Fig. 3C is generated across both terminals of the oscillator capacitor C1.
  • the triangular waveform oscillation circuit 3 in the present embodiment is adapted to output this triangular waveform voltage to the comparison circuit 4.
  • cycle time T2 of the triangular waveform voltage after the increase of the voltage of the input power source Vin is decreased compared with cycle time T1 of the triangular waveform voltage before the increase of the voltage of the input power source Vin, thus a triangular waveform voltage with a higher frequency is outputted.
  • the triangular waveform voltage outputted from the triangular waveform oscillation circuit 3 is inputted to the non-inverting input terminal of the comparator COMP2 of the comparison circuit 4, and the threshold voltage V th resulting from the output voltage V of the constant voltage circuit 1 divided by the resistors R13 and R14 is inputted to the inverting input terminal of the comparator COMP2. Consequently, the rectangular waveform generated at the output terminal COMP2o of the comparator COMP2 is at the high level when the triangular waveform voltage is higher than the threshold voltage V th , and is at the low level when the triangular waveform voltage is lower than the threshold voltage V th , thus a rectangular waveform voltage is generated.
  • the threshold voltage V th of the comparator COMP2 is set to stay substantially at the halfway level between the two threshold voltages V TH and V TL of the comparator COMP1, and the duty ratio of the rectangular waveform voltage outputted from the output terminal COMP2o of the comparator COMP2 is set about at 50% regardless of frequency.
  • Fig. 4B shows rectangular waveform voltages which correspond respectively to the triangular waveform voltages indicated by solid and dashed lines, and which are transformed at the threshold voltage V th . Since the rectangular waveform voltage has its frequency increased with its duty ratio kept substantially constant while the voltage of the input power source Vin increases, the time periods at the high level and the low level in one cycle time are shortened. As described above, the rectangular waveform voltage is adapted to drive, via the drive circuit 5, the switching element Q1 of the inverter circuit 6, for example, such that the rectangular waveform voltage is at the high level when the switching element Q1 is turned on. Consequently, it will be understood that the on-time of the on/off operation of the switching element Q1 is caused to decrease with an increase in the voltage of the input power source Vin.
  • Figs. 11 to 15 it is understood that the peak value of the current Id increasing during one on-operation of the switching element Q1, and the peak value of the pulse voltage Vds generated at the primary side TRp of the transformer TR at the off time of the switching element Q1 are decreased with an increase in the voltage of the input power source Vin, which means that the energy stored in the transformer TR during one on-operation of the switching element Q1 is reduced.
  • the above-described variation of the peak value of the voltage Vds corresponding to the variation of the voltage at the input power source Vin is shown in Fig. 16.
  • the operating frequency of the switching element Q1 is varied with the duty ratio of the input power source Vin maintained substantially constant, whereby the energy stored at the transformer TR during one on-operation of the switching element Q1 is caused to vary so as to cancel out the variation of the voltage of the input power source Vin, and consequently the electric power applied to the transformer TR is maintained substantially constant.
  • the light amount of the rare gas fluorescent lamp DL connected to the secondary side TRs of the transformer TR is maintained substantially constant, even if the voltage of the input power source Vin varies, which is evidenced by the graph of Fig. 17.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
  • Inverter Devices (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
EP05017710A 2004-09-10 2005-08-16 Rare gas fluorescent lamp lighting apparatus Withdrawn EP1635621A2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2004264191A JP4174679B2 (ja) 2004-09-10 2004-09-10 希ガス蛍光ランプの点灯装置

Publications (1)

Publication Number Publication Date
EP1635621A2 true EP1635621A2 (en) 2006-03-15

Family

ID=35447465

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05017710A Withdrawn EP1635621A2 (en) 2004-09-10 2005-08-16 Rare gas fluorescent lamp lighting apparatus

Country Status (6)

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US (1) US7274152B2 (ja)
EP (1) EP1635621A2 (ja)
JP (1) JP4174679B2 (ja)
KR (1) KR20060050491A (ja)
CN (1) CN1747617A (ja)
TW (1) TW200610445A (ja)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004100614A1 (en) * 2003-05-07 2004-11-18 Koninklijke Philips Electronics N.V. Current control method and circuit for light emitting diodes
US7615940B2 (en) 2006-06-30 2009-11-10 Intersil Americas Inc. Gate driver topology for maximum load efficiency
JP5298452B2 (ja) * 2007-04-04 2013-09-25 株式会社豊田自動織機 モータインバータ制御装置及びモータ制御方法
JP2009037859A (ja) 2007-08-01 2009-02-19 Funai Electric Co Ltd 蛍光管用電源、バックライト
JP2011119236A (ja) * 2009-10-30 2011-06-16 Anden 負荷制御回路
ES2755073T3 (es) 2011-02-23 2020-04-21 Toshiba Mitsubishi Elec Ind Dispositivo de conversión de energía
US20120217895A1 (en) * 2011-02-24 2012-08-30 Taiwan Sumida Electronics Incorporated Lamp tube driving device, lamp tube module, and lamp tube driving system
CN106304525A (zh) * 2015-06-01 2017-01-04 海洋王（东莞）照明科技有限公司 可调色温的led驱动电路

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2619370B2 (ja) * 1986-10-11 1997-06-11 松下電工株式会社 放電灯点灯装置
JPS63174568A (ja) * 1987-01-14 1988-07-19 Matsushita Electric Works Ltd インバ−タ装置
JPH0696889A (ja) * 1992-09-10 1994-04-08 Ikeda Electric Co Ltd 放電灯点灯装置
JPH07142178A (ja) * 1993-11-22 1995-06-02 Sony Corp ランプ駆動回路
JPH1041081A (ja) * 1996-07-22 1998-02-13 Minebea Co Ltd 放電灯点灯装置
JPH1126184A (ja) * 1997-07-04 1999-01-29 Canon Inc 蛍光灯駆動回路及びこれを用いた画像形成装置
JP3880246B2 (ja) 1999-06-29 2007-02-14 Ｎｅｃライティング株式会社 希ガス放電灯の点灯装置
JP2002352989A (ja) * 2001-05-25 2002-12-06 Mitsubishi Electric Corp 放電灯点灯装置

Also Published As

Publication number Publication date
TW200610445A (en) 2006-03-16
US20060055342A1 (en) 2006-03-16
CN1747617A (zh) 2006-03-15
US7274152B2 (en) 2007-09-25
KR20060050491A (ko) 2006-05-19
JP4174679B2 (ja) 2008-11-05
JP2006079997A (ja) 2006-03-23

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